Fabric conditioning compositions, in particular fabric softening compositions to be used in the rinse cycle of laundry washing processes, are well known. Typically, such compositions contain a water-insoluble quaternary-ammonium fabric softening agent, the most commonly used having been di-long alkyl chain ammonium chloride.
The anti-harshening effect of cellulase on fabrics is known from e.g. FR 2 481 712 or GB-A-1 368 599, and cellulase's fabric care benefits, are disclosed in, e.g., EPA 269 168, all incorporated herein by reference in their entirety. Cellulases have been mainly described, however, for use in detergent compositions to be used in the main wash cycle of laundry processes, and have found some commercial application in this context.
The use of cellulases in rinse added fabric softener compositions has apparently been commercially pursued only recently. Potential issues which appear to be resolved include the provision of acceptable stability of the cellulase in such compositions upon storage; the effectiveness of cellulase use in the rinse cycle following a normal detergent wash cycle despite the fact that the rinse cycle conditions are typically of shorter duration and lower temperatures than used in the wash cycle; and the resolution of concerns around the potential for fabric damage if too high cellulase activity is present in the rinse cycle, e.g., by carry over of cellulase activity from cellulase-containing detergents in the wash cycle.
It has previously been discovered that rinse added fabric softener compositions can be formulated to provide cellulase activity within certain limits during normal use conditions so as to provide fabric softening benefits with an acceptable impact on fabric wear. It has also been found that cellulase in fabric softener compositions at low pH is remarkably stable and that cellulase is further stabilized for storage by the addition of antioxidants and/or chelants. Formulation of fabric softening compositions can be accomplished over the entire typical pH range of fabric softening agents, including pH of 5 to 7 for traditional fabric softening actives, while achieving both effectiveness and fabric safety benefits following prolonged storage.